In-line roller skates are configured with a frame which supports a plurality of in-line rollers. The frame is attached to a boot or shoe and includes two sidewalls which extend downwardly and define a cavity therebetween. Typically, each of the rollers is rotatably supported by an axle which is transversely inserted through apertures aligned in opposed locations of the sidewalls. The axles extend across the cavity to enable the wheels or rollers to rotate with respect thereto. Thus, the axles can be exposed to large tensile, bending, and impact forces, especially at critical joints, and therefore must be designed to withstand these types of loads.
Previously, two-piece axles and three-piece axles have been employed to assemble the wheels to the associated frame component. The two-piece axle includes an integral first member with a barrel-like portion which extends across the length of the cavity defined by the two sidewalls. The first member includes an internal threaded portion which receives a second member. Each of the first and second members have heads which are positioned on the outer surfaces of the sidewalls to secure the axles thereto. Unfortunately, this configuration positions the thinnest portion of the shaft within the aperture of the sidewall, which concentrates stress at this thinnest portion and therefore can reduce the strength and durability of the axle significantly. In addition, for each differently sized frame or different roller configuration (e.g., roller size), a different specifically-sized first member and/or second member must be carried in inventory. The increased inventory can, in turn, increase the manufacturing costs associated therewith.
One example of a roller axle is proposed by Gierveld in U.S. Pat. No. 5,046,746. As described, the axle is formed by two threaded bolts which directly engage with a bearing shaft component. Unfortunately, like the two-piece axle described above, this configuration places the thinnest portion of the axle within the aperture of the sidewall, which can concentrate stress at this thinnest portion and therefore reduce the strength of the axle. This design also employs multiple relatively complex axle-to-frame mounting components. Further disadvantageously, this design provides limited interchangeability with alternatively configured frames.